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Sensors / Detectors: Resistance
Meters
Last Updated on:
Saturday, April 26, 2008 08:31 AM |
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Sensors / Detectors -- Main Page |
| Circuits Designed by Dave Johnson, P.E. : |
- UL GROUND RESISTANCE TESTER
UL requires that an electrical system using a metal chassis earth ground connection have a resistance of less than 0.1 ohms. This resistance must be tested with actual line current in
excess or 10 amps. The circuit shown uses a couple of LEDs to indicate if in fact the resistance is less than 0.1 ohms. It uses a modified transformer to produce a 2.5vac output
with at least 10 amps of supply current.
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| Links to electronic circuits, electronic schematics, designs for engineers,
hobbyists, students & inventors: |
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Accurately measure resistance with less than perfect components: 11/11/04 EDN Design Ideas / (added 5/05) For
transducers, such as strain gauges or thermistors, you must accurately and inexpensively measure resistance using circuitry built with imperfect components and in which gain and offset
errors can significantly limit the accuracy of ohmic measurements. The right circuit topology makes it possible to eliminate most error terms while measuring ohms, leaving the accuracy to be
determined by jus... |
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AN611: Resistance and Capacitance Meter using a PIC 16c622: Microchip Application Note - Published 26-Aug-97
(added 2/06) |
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Calculation of transil apparent dynamic resistance: AN575 (Circuit / schematic design added 6/06) |
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Grounded resistor tunes Oscillator: 05/29/03 EDN Design Ideas / (added 1/05) To vary the frequency of
any sine-wave oscillator, you should use a pair of ganged variable resistors, and you should thoroughly match their characteristics over the entire variation range to satisfy the
oscillator's balancing conditions. This restriction leads to problems in the tuning range and high cost, thereby limiting the range of applications.... |
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Optimize linear sensor resolution: 03/07/02 EDN Design Ideas / (added 1/05) A wide variety of sensors
and transducers of physical phenomena work via the mechanism of variable resistance. These devices sense temperature, light, pressure, humidity, conductivity, and force, for example. Such
sensors measure the physical parameter of interest by reading out the inherent parameter-sensitive resistance or conductance. ... |
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Resistance calculator yields precise values: 08/03/95 EDN-Design Ideas / (Circuit / schematic design added 6/06) |
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Resistance, DC Current, AC Current, Frequency and Period Measurement Errors in DMMs (5988-5512EN): Aligent
Application Note (added 4/08) |
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